Using the Knog Blinder Square Twin Pack is easy. First, use the silicone straps to attach the lights to your bike. You can use the smaller strap for bars and seat posts between 22 and 32mm in diameter, and the larger one for tubes with a circumference up to 200mm. When it's time to charge, just plug the integrated USB directly into a USB port. It takes about 4 hours to fully charge. Keep an eye on the red LED next to the button; if it lights up, it's time to recharge. The lights are 100% waterproof, so you don't have to worry about using them in the rain. However, to keep them in good condition, avoid exposing them to extreme temperatures. When not in use, store them in a cool, dry place.